An antibiotic-resistant Corynebacterium sp. has been isolated with increasing frequency from severely immunosuppressed patients at the Clinical Center and now also at other Cancer hospitals. Isolates of this organism were collected and further characterized since this Corynebacterium seems to be an un-named species designated as group J/K with little information currently available as to its frequency and distribution. Screening cultures indicate that hospitalized patients may harbor the organism particularly on axillary and inguinal skin sites. Isolation is greater from males than females, and patients may frequently harbor the organism on admission to the N.I.H. hospital, indicating prior colonization. Colonization occurs in both cancer and non-cancer patients, but bacteremia has occurred exclusively in cancer patients, specifically in those with hematologic as opposed to solid neoplasms.